Thanks Raghunathan for your reply.
You are right, I felt hurt because of the minus 100 points, what it suggests is that, I did not take the efforts to search properly.
The fact is I was not aware that a search on "PCAT" and a search on "PC AT" makes so much of difference.
Everybody learns from mistakes. I have learnt it now.
By the way I had searched the application note for PCAT, implemented it and found that it is ok for basic communication, but it is not good enough to implement the full keyboard, so I had asked for help on this forum. For which I got the necessary application note I was looking for from Charles and I am feeling really grateful to him rather indebted to him.
No hard feelings with anybody on this forum, because time and again this forum has helped me a lot, and some day(s), I will contribute my efforts to this forum.

Thanks again.
Kiran